Franklin booted five goals in the first half and finished with eight majors in the 18.7 (115) to 13.8 (86) triumph in front of 53,553 fans on Sunday.
Naitanui, playing his first AFL match since rupturing the ACL in his left knee in August 2016, showed he had lost none of his ruck magic by producing a series of sublime taps to advantage throughout the match.
West Coast led by one point early in the second quarter on the back of Naitanui’s strong performance in the ruck.
But with Franklin dominating in his battles against defenders Tom Barrass and Will Schofield, it seemed just a matter of time before Sydney pulled away.
The 31-year-old booted three goals in the opening term.
And by the time he kicked his seventh goal midway through the third quarter, Sydney led by 30 points and it looked to be game over.
However, Naitanui helped turn the tide late in the third term as West Coast’s midfield started to gain control.
Naitanui sent the crowd into raptures when he won a holding the ball decision in the forward pocket and then snapped truly from the set shot.
And when Mark LeCras booted a goal after the three-quarter time siren – West Coast’s fourth in a row – the margin was just five points.
But once again it was Franklin who stepped up when Sydney needed him most.
With the Swans leading by just 11 points, Franklin outbodied Barrass to take a mark, before running into the open goal to give Sydney some much-needed breathing space.
West Coast continued to fight hard, but a freak scissor-kick goal from Luke Parker killed off their comeback for good.
Will Hayward, who was a late replacement for Sam Reid (hamstring), booted two goals in the final minute to blow out the margin.
LeCras and Jack Darling booted three goals apiece for the Eagles, while Naitanui finished with 33 hit-outs, 12 disposals, and one goal.
Franklin tallied 21 possessions, nine marks, five tackles to go with his 8.1.
For the trivia buffs, Sydney defender Jake Lloyd etched his name into history with the first AFL goal at Perth’s new $1.6 billion stadium.
© AAP 2018
SYDNEY 5.1 9.5 11.6 18.7 (115)
WEST COAST 4.2 5.3 10.7 13.8 (86)
Goals: Sydney: L Franklin 8 W Hayward 2 D Towers G Hewett I Heeney J Kennedy J Lloyd K Jack L Parker Z Jones. West Coast: J Darling 3 M LeCras 3 C Masten E Yeo J Waterman L Duggan L Ryan N Naitanui S Hurn.
Best: Sydney: L Franklin J Kennedy L Parker J Lloyd I Heeney Z Jones. West Coast: N Naitanui L Shuey E Yeo M LeCras S Hurn L Jetta.
Umpires: Jeff Dalgleish, Dean Margetts, Nicholas Foot.
Official Crowd: 53,553 at Optus Stadium.